Fabrication of synergistic calix[4]arene–PVC–MWCNT–graphite films for fast and sustainable adsorption of dye pollution

The increasing discharge of dye pollutants, particularly methylene blue (MB), into aquatic systems represents a critical environmental challenge due to their persistence, toxicity, and resistance to biodegradation. In this study, we report the synthesis and characterization of a novel flexible adsorbent film composed of tetraformyl calix[4]arene, polyvinyl chloride (PVC), multi-walled carbon nanotubes (MWCNTs), and graphite (TfCPMG). The calixarene moieties introduce highly active formyl functionalities and aromatic cavities, enabling strong electrostatic and π-π interactions with cationic dyes, while the MWCNT and graphite components provide structural reinforcement, conductivity, and additional adsorption sites. Structural characterization using FT-IR, Raman, BET, and FE-SEM confirmed the successful integration of these components and revealed a heterogeneous, porous surface favorable for adsorption. Adsorption performance was systematically evaluated by examining the effects of pH, adsorbent dosage, contact time, and initial MB concentration. The TfCPMG film exhibited an optimal removal efficiency of 80% for a 5 ppm MB solution at pH 9, with rapid kinetics reaching equilibrium within 10 min. Notably, the adsorbent maintained > 78.5% removal efficiency after ten adsorption-desorption cycles, demonstrating excellent reusability and stability. Comparative analysis against previously reported adsorbents highlights the superior efficiency, low cost, and operational simplicity of the fabricated film. These findings establish the TfCPMG flexible film as a high-performance, scalable, and sustainable adsorbent, offering a promising solution for practical wastewater treatment and dye pollution remediation.